4.0 For Sale Blown Freeze Plug

[backporch]

An engine from a 96 is available. Seller says he got the low mileage engine in a Ranger recently and it had a blown freeze plug. That has been repaired and the engine was pulled and ready for sale.

There is more to the story and I guess it makes sense that the truck he was going to use the motor for is being sold.

My concern is what would cause a freeze plug to blow? Would it be somebody didn't use antifreeze? Does anyone have experience with an engine blowing a plug and running ok again. Loss of coolant to me sounds like it could have resulted in heat related issues if it happened while driving.

Could it have rusted so badly to dislodge without a noticable leak first? Is that a sign of neglect not changing anti-freeze. Seller sounds reasonable, but I am just not comfortable with it. Any thoughts?

 

[Biohazard_40]

If it makes you nervous, walk away. If the price is right, try to get some guarantees. You could pressure test the block if it’s all together with some ingenuity. Plug one hose and pressure up the other with a gauge and see how long it holds 15-20psi. Many reasons for a freeze plug to fail, the most common I’d say is no antifreeze in the water and there was a hard freeze. If that’s the case chances are good the block was damaged and more often than not, beyond repair.


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[Mountain12]

I would walk away if not run!

 

[alwaysFlOoReD]

The 4.0 in my race truck froze up when I forgot to put antifreeze in at the end of the season. It's currently in my daily driver with no problems. It blew a lower frost plug which I fixed with a rubber expanding plug. Previous to that I found the head frost plugs had pinhole leaks from rust which I changed out.

Now that I think back, I did have a problem with the impeller on the pump not connected to the shaft. That may have been from being frozen and fired up. In fact I can almost guarantee that is what caused the pump failure.

Depending on price I would take a chance after doing as biohazard suggested along with a compression check or leak down test..

 

[backporch]

I think a pressure test wouldn't be too difficult. I did something similar for my pool, where I connected a barbed pvc connector with a cap and shrader valve into the end of the plumbing, pressurized it to 20 psi and checked it hours later for a pressure drop. Should be easy to do that to the radiator hoses, plug one and the other one has a plug with a valve.

Compression test would be valuable too!

Thanks!!

 

[alwaysFlOoReD]

There is an aftermarket fitting that goes into the heater hose. It has a cap that threads off and is used for antifreeze fills IIRC. I drilled a hole in the cap and pulled a tire valve into the hole. I used copper end caps of the correct size to plug the rad hoses as the engine was out of the vehicle. Worked great and was cheap. A valve in a rad end cap would work too.